MACH I Member
Joined: Nov 2009
As others have said here, look into replacing the speakers. I would however take it one step further and drop in an amp and a moddest subwoofer in the trunk (around 200-300w should be all thats really needed).
I did this in my 05 and it sounded AMAZING (and the shaker 500 is a bit better now than it was in 05).
2011 Shelby GT 500: C&L CAI, Roush GT 500 Performance axlebacks, Steeda 2.65 Supercharger pulley with idler/belt tensioner, Ford SVT Custom Racing Tune, SVT package, Glass roof, Tech package
Gone: 2011 GT/CS Black
Gone: 2010 Sterling Gray GT, Track Pack